Adhesives and sealants used today in construction, transportation, industrial, electronic, consumer, and numerous other applications are advanced materials based on state-of-the-art synthetic polymer technologies. They have existed for thousands of years, however. Pitch and other natural materials have been used to hold materials together since before civilization was established. Today, adhesives enable the joining of very different materials (unlike conventional physical fasteners), leading to the introduction of new plastics, composites, and other materials in construction, aerospace, and other applications. These materials can also be bonded with adhesives into shapes with greater flexibility than is possible with conventional screws. As a result, both new technologies and existing products have improved durability, reliability, quality, performance, and aesthetics. Manufacturing processes have also been improved, and designers have much greater flexibility.
Since the use of the first phenol-formaldehyde resins, adhesive manufacturers have developed products based on chlorinated rubbers, other formaldehyde-based resins acrylates, polyvinyl acetate, epoxies, and cyanoacrylates. Pressure-sensitive adhesives entered the market in the 1970s followed by hot-melt adhesives in the 1980s. The wide range of chemistries available today has led to the formulations of many different types of adhesives with many different properties, including multifunctional systems that do more than bond materials together.
One of the biggest end-use applications for adhesives is hygiene products, including baby diapers, adult incontinence, and feminine hygiene products. While water-based adhesives were first used in disposable diapers, today hot-melt adhesives based on styrene block copolymers are used because they allow for different shapes that lead to greater fit and comfort combined with improved leak resistance. The global hygiene market is growing at > 7-8%, with significantly higher growth rates in the emerging geographies, according to Karin Katzer, global associate marketing director for Dow Elastomers. “The purchasing power in emerging markets is increasing and, as a result, people have more money to spend on disposable products such as diapers and feminine hygiene products,” she observes.
In addition, demographics and lifestyle changes are altering our global landscape, and they are also changing the global adhesives and sealants landscape, according to Katzer. “In almost every major region around the world, people are living longer. As a result, the potential global market for adult incontinence is growing,” she says.
In the automotive market, adhesive use has evolved dramatically to the point where adhesives are widely used in car interiors, improving the appearance, comfort, and safety of cars. As auto makers introduce lighter-weight materials to increase fuel efficiency, adhesives are also increasingly being used for the exterior manufacture of cars, according to Keith Oleson, field marketing manager for Arkema Coating Resins. “Similarly, in the aerospace industry, manufacturers are paying more attention to epoxies and polyurethane technologies, primarily in weight-saving designs as graphite composites continue to replace aluminum components,” he says.
In the construction industry, advances in adhesive technologies have facilitated the use of synthetic flooring materials, both for interior and exterior (e.g., rubber sport courts) applications. Improvements in adhesive performance have also contributed to the growing use of luxury vinyl tile (LVT) in demanding environments such as hospitals. Silicones are receiving a lot of attention right now due to their performance in building glazing applications, according to Oleson. “This interest is a direct result of manufacturers anticipating and looking for solutions to extreme weather events,” he comments. Challenges for adhesives and sealants applications mirror those faced in the construction industry as a whole, according to Christopher Hummel, marketing manager for Adhesives and Construction Materials with BASF, and include the need for increased durability, resistance to moisture, and ease of use. “These challenges become greater as building codes become more demanding,” he states.
There is also a difference in demand for adhesive and sealant performance capabilities in do-it-yourself (DIY) and contractor applications, according to Brendan Gallery, marketing specialist for Sealants with BASF. “DIYers are more interested in specialized application solutions for a specific job (i.e., kitchen, bath, quick-dry paintable, window/trimming, roofing, HVAC, fire-stop, swimming pools, etc.),” he says. The DIY market is also driven by ease of use, both in application and clean-up as well as using more environmentally friendly products. “Contractors on the other hand,” Gallery remarks, “are more focused on price, variety of use, adherence to difficult substrates, durability, and rapid-cure times, as well as avoidance of APEO, ammonia, and plasticizers. Saving time on the job and reducing labor costs are critical for contractors as the labor force tightens.”
In the packaging industry, meanwhile, advances in adhesive technology enabled the use of filmic substrates for flexible packaging, and in particular polyethylene terephthalate (PET), which does not stick well to many other substrates. Increased urbanization is currently playing a large role in driving adhesive industry growth as more consumers move to the city and buy their food already packaged rather than growing it themselves, according to Katzer. In addition, she notes that as consumer lifestyles become more fast-paced and on-the-go, convenient, single-use packaging becomes more widespread. More stringent norms and regulations driven by consumer food safety concerns are also impacting adhesive and sealant demand. Finally, she adds that the increasing need to fight the global food waste battle calls for packaging that can keep food fresher longer and be easily resealed.
On the other hand, Katzer notes that there is a decline in demand for adhesives in bookbinding driven by digitalization.
Overall, Arkema is seeing the greatest growth in the building, construction, paper, and packaging markets, according to Oleson. He notes that the most significant trends in the industry center around a few topics, specifically rapid industrialization, regulatory standards, chemical scrutiny, and sustainability/energy efficiency. There are some regional differences: in more mature markets, such as North America and most of Europe, growth is closely aligned with the GDP, while in emerging markets where there is increased economic activity, most notably in Asia Pacific, more rapid growth is occurring, according to Oleson. In all regions, Arkema is seeing increased regulatory standards associated with greater scrutiny of the environmental fate of chemicals and VOC emissions.
New adhesive and sealant technologies are being developed in response to these trends. “Adhesive technologies that can enhance customer sustainability profiles and reduce energy consumption attract attention. Also, technologies that aid in the manufacturing process, producing easy mixing and broad application temperature range are in high demand,” Katzer asserts. Oleson adds that increasing product durability remains a key driver in the development of new adhesive and sealant products, as does the need for new ways to decrease cure times and make application easier in the field. “We expect increasing demand for the elimination of solvents and greater use of environmentally benign raw materials and products, as well as a continued focus on improved product performance,” he remarks.
For instance, the elimination of external plasticizers in waterborne sealants, in part driven by changes in the regulatory environment, has led to improved product performance and reduced environmental impact, according to Oleson. One of the leading drivers for new product development is changes in regulations, agrees Hummel. “In the construction industry,” he observes, “both building codes and product content regulations (i.e., Prop 65 requirements in California) are important. These regulations change and tighten over time, causing formulators to use new chemistries in product development to attain the best possible solutions,” he explains.
Acrylic technologies are experiencing higher than average growth because they are solvent-free and low-VOC, meeting more stringent environmental regulations, according to Gallery. He adds that acrylics are easier to apply to a wide variety of substrates and have excellent paint-ability. In construction applications, Hummel points to the development of adhesives and sealants that are robust, clear, and paintable. “This trend aligns with the general construction industry’s need for ease of use, satisfying increased consumption in the DIY segment, and a tight skilled labor pool,” he observes.
With the hot-melt adhesive market growing so rapidly and strong growth happening in emerging markets, Katzer notes that it is increasingly important to deliver industry-leading solutions at a greater volume. “Dow’s new High Melt Index specialty and conventional polyolefin elastomer ethylene derivative production facility in Freeport, TX opening in 2018 is an example of how Dow is committed to meeting demand and need of the industry to ensure supply reliability,” she says.
There are also ongoing efforts industry-wide to increase the use of renewable raw materials in product formulations, according to Oleson. Several biobased raw materials are in fact available for the formulation of renewable adhesives and sealants, according to Doris de Guzman, senior consultant for Biomaterials with Tecnon OrbiChem. Those attracting the most attention include succinic and other diacids, natural-oil polyols, CO2-based polyols, bio-isobutanol and 1,4-butanediol, biobased isocyanate alternatives, furan dicarboxylic acid (FDCA) and esters and biobased epichlorohydrin. Several companies are also producing biobased solvents (acetone, ethyl acetate) that have potential use in adhesive and sealant manufacturing.
“We can expect adhesive and sealant manufacturers and their suppliers to continue to innovate to bring cost-effective, high performance solutions while meeting increasingly stringent global regulations,” Katzer states. “Additionally, we will continue to see the use of sustainable adhesive materials that increase sealing mileage and can in turn enhance customer sustainability profiles. Finally, there is customer demand for polymers that can be used on a wider variety of products to simplify supply chain, logistics, and reduce cost,” she concludes.